Learn how JavaScript’s built-in functions like map() and filter(), as well as compose() and chain(), support a more elegant handling of JavaScript arrays.

The JavaScript method, Array.map(f) is a pure function in that it takes a function as a parameter. That last point about pure functions warrants further exploration. First-order functions vs. pure ...

The Map object in JavaScript provides several key methods for adding, retrieving and manipulating key-value pairs. The set() method is used to add or update a key-value pair in a Map.